Animal imaging, using a Magnetic Resonance Imaging (MRI), Computer Tomography (CT), and Positron Emission Tomography (PET), plays an important role in basic neuroscience and drug discovery. Referring to FIG. 1, for example a conventional imaging apparatus 10, such as an MRI scanner, is illustrated. As shown, a typical MRI apparatus forms a strong magnetic field around the area to be imaged. In one embodiment, a conventional MRI apparatus 10 includes a patient table 14 configured to receive a patient 12 thereon in which the patient 14 is temporarily exposed to an oscillating magnetic field applied by a Radio Frequency (RF) coil 16 of the MRI apparatus 10 at the appropriate resonant frequency. The excited hydrogen atoms in the tissue of the patient 14 become excited by the oscillating magnetic field applied by the RF coil 16 and emit a radio frequency signal which is then detected and measured by a radio receiver coil. The radio receiver coil could be the same one as the RF coil 16 (but switched from RF transmitter mode to RF reception mode) or a separate RF receiver coil for better sensitivity. Typically, the radio frequency signal received by the radio receiver coil 16 can be made to encode position information by varying the main magnetic field using gradient coils 18, which are rapidly switched on and off to create the characteristic repetitive noises of an MRI scan. The contrast between different tissues is then determined by the rate at which excited atoms return to an equilibrium state.
A typical imaging session using the MRI apparatus 10 can take over 45 minutes and can last as long as several hours, depending on experimental protocols, during which the subject being imaged must remain still during the imaging procedure, otherwise imaging artifacts would occur. In particular, animals being imaged, such as rodents in an awaken state, are not readily compliant with the restricted movement required when being imaged.
Current techniques for imaging animals in an awaken state aim to train them to remain still for a prolonged period of time during imaging with the aid of a body restraint along with head fixation using a bite bar and/or ear bars or head mount. However, physically restraining the animal can induce stress, thereby resulting in unavoidable movement of the stressed animal in many cases.
Due to the limitations of imaging animals in an awaken state, a majority of animal imaging is conducted when the animal is under anesthesia. However, anesthetics compromise brain functions of the animal under anesthesia, while some anesthetics can directly interact with the pharmacological compounds being tested, thereby potentially skewing data being collected.
As such, there is a need for improvements in systems and methods for imaging of animals in an awaken state.